In today's wireless communication networks, Public Land Mobile Networks (PLMNs) have been established to provide land mobile telecommunications service to user devices such as electronic book readers, cellular telephones, personal digital assistants (PDAs), portable media players, tablet computers, netbooks, and the like. Generally, each service provider operates its own PLMN, and the number of PLMNs in a country may vary from a single PLMN in a small country to as many as fifty or more in a large country like India.
When a user device is located outside of the area covered by its own service provider's PLMN (the Home PLMN), the user device attempts service acquisition on another PLMN, which is commonly known as roaming. Typically, a prioritized list of PLMNs that the user device is allowed to access is stored on a Subscriber Identity Module (SIM) card. The entries and prioritization in the list are usually based on agreements contracted among the various service providers. When a user device operates in the automatic selection mode, the user device consults the preferred PLMN list defined by the network operator, and attempts to register on a PLMN in accordance with the listed priority. If registration cannot initially be obtained on the home PLMN, the user device will then attempt to register on the next highest priority PLMN on the list, and so on, until service is acquired. However, due to limited storage space on SIM cards, preferred PLMN lists stored on SIM cards typically cover such regions as U.S., Canada and Europe and do not cover several regions, including, for example, India, South America and Asia. When the SIM card does not have a preferred PLMN list for the region in which the user device is currently located, the user device identifies PLMNs with a sufficient signal strength that are present in the current location and randomly selects one of these PLMNs. If the selected PLMN does not have a roaming agreement with the service provider of the user device, the selected PLMN rejects the user device's request for service and the user device has to select a different PLMN. In regions that have a large number of PLMNs (e.g., India or Asia), a user device may have to hop between many different PLMNs until it is able to acquire roaming service.
When a user device operates in the manual selection mode, the user is given an opportunity to select an available PLMN. In particular, the user will have to review the list of PLMNs available at the current location and select a specific PLMN from the list. This is likely to be inconvenient and time-consuming for the majority of users who usually do not know which of the available PLMNs have a roaming agreement with their service providers.